Reboiler



P. F. D OUGHERTY REBOILER Filed Aug. 5, 1954 INVENTOR. 1 PATRICK F.DOUGHERTY BY I " E-Kira nited States Patent 2,857,325 REBOILER ChesterHeights, Pa., assiguor to Philadelphia, Pa., a corporation of Patrick F.Dougherty, Sun Oil Company, New Jersey This invention relates to heatexchange apparatus, and more particularly to heat exchange apparatus inwhich one fluid is at least partially vaporized.

Reboilers used in the petroleum industry represent one form of equipmentto which the improvement of this invention is particularly adapted. Aspresently developed, one form of accepted reboiler provides a heatexchange section and a surge section. In the heat exchange portion theliquid to be vaporized is in close contact with the heating means,usually tubes, through which hotter fluids flow. The depth of thevaporizing liquid is maintained between weirs bounding this section. Inoperation, the liquid to be vaporized spills over the weir into thesurge section where the vapors accumulate and from which they pass toadditional equipment for further processing.

It is the present practice to immediately conduct the vapors from thesurge section to the next processing step. A conduit connected to theouter shell of the heat exchanger, above the surge section, accumulatesand conducts the vapors therefrom. There results, because of temperaturechange and unrestricted release of the heated vapors, a contrary flow ofcondensed and entrained material which greatly reduces the efiectivenessof the device.

The principal object of the present invention is therefore to provide animproved means for removing the vapor products from a reboiler and theresulting presentation to the next process step of a better prepared andcontrolled petroleum fraction.

Incidental to this principal object are the additional objects ofproviding better temperature control in effecting the vaporizing step,more efiicient separation of the vaporized and non-vaporizedconstituents of the heat receiving liquid, and more eflicientutilization of the space in which such reboilers are required to benested between and adjacent other apparatus.

With the above and other objects in view, all of which will be fullydisclosed in the course of the following description, the inventionconsists in combining the dual sectioned reboiler with an improvedentrainment breaker to improve the quality and condition of theextracted vapor. By dimensioning and positioning a vapor withdrawingconduit within the reboiler shell and relative to the heat exchange andsurge chambers, improved operation is secured.

The accompanying drawing is a longitudinal sectional view through such adual chambered reboiler illustrating a practical example of theinvention.

Referring more specifically to the figure of the drawing, the reboilershell or casing 10, divided into the heat exchange section or chamber 12and the surge chamber 14 by the weir 16, is provided with a tubularheater 18 in chamber 12. Inlet 20 and outlet 22 conduct the heatingmedium to and from heater 18 to heat the liquid 24. The liquid inlet 26admits the liquid 24 to be vaporized to heating contact with tubularheater 18 where it reaches the depth of the weir 16, spills over andempties out of outlet 28. The agitation of spilling over the weir and.the heat transfer causes the desired vapors to release and rise in thesurge chamber to the entrainment breaker 30,

2,857,325 Patented Oct. 21, 1958 A baffle section 32 forms the entranceof the entrainment breaker 30. This may be conventional baffles or vanesintended to change the direction of the entering vapors and presentaccumulating surfaces for entrained droplets, or it may be acommercially available element known to the art as demisters serving thesame purpose. In either case the purpose is to remove the heavier liquidparticles from the vaporized material in the vicinity of the surgechamber 14.

The entrainment breaker 30 is extended in the shell contrary to thedirection of movement of the liquid 24 from which the vapors aredesired. It passes through the surge chamber, over the weir and entersthe heat exchange portion to exit there from the shell, as shown.

By thus positioning and dimensioning the entrainment breaker 30 anadditional path of temperature controlled travel is available to thevapors freed of entrained liquid before it passes through the outlet 34to the next step in the process. The temperature of the breaker 30 ishigher throughout its length than the liquid supporting portion of thesurge chamber because of elevation in the shell, and differs intemperature in its length because the outlet is in the heat exchangezone while the inlet is in the relatively cooler surge chamber.

The improved operation of the device will be evident at this point.After leaving the heat exchange contact with tubular heater 18,vaporizing liquid 24 spills over the weir 16 into the surge chamber 14,which is relatively cooler. Vapors released here because of absorbedheat and agitation move upward in the shell 10 to the inlet ofentrainment breaker 30, shown as baffled section 32. The conduit formingthe breaker 30 is of consistently higher temperature than the vapors itreceives and is progressively warmer throughout its length from inlet 32to outlet 34 because of position relative to heater 18. This initial andprogressively higher temperature condition maintains the received vaporsin the vapor stage and conditions them for transfer through the outlet34.

What is claimed is:

In a reboiler for use in refining petroleum in which a casing is dividedinto heat exchange and surge sections by a transverse weir, said weirbeing of suflicient depth to provide a body of liquid petroleum in theheat exchange section, and inlet and outlet conduits for the heatexchange and surge sections respectively, the improvement for collectingvapors in the surge section and conducting them from the reboiler inbetter condition for further refining operations comprising a conduitarranged longitudinally within the casing having an inlet end above thesurge section and an outlet end passing through the reboiler casingabove the heat exchange section, said conduit being suspended in saidcasing to fully expose the complete periphery over the length thereof tothe internal temperature of the reboiler, and baffle means positionedonly at said inlet end of the conduit above the surge section toimmediately intercept entrained liquid particles and return them to thesurge section.

References Cited in the file of this patent UNITED STATES PATENTS1,407,380 Chenard Feb. 21, 1922 1,646,449 DYarmett Oct. 25, 19272,032,546 McNeil et al Mar. 3, 1936 2,106,583 Webb Ian. 25, 19382,139,985 Tali Dec. 13, 1938 2,320,366 Leaf June 1, 1943 2,665,565 ParksIan. 12, 1954 OTHER REFERENCES Kern: Process Heat Transfer, firstedition (1950), pp. 471, 472.

